Dry size and method of making



Feb. 2, 1943. E. 5. WILSON 2,310,005

DRY SIZE AND METHOD OF MAKING Filed April 1a, 1940 --I2 COMPACTING EVANSl4 BLOW CHAMBER AUTOCLAVE HAMMER MILL ll] SEPARATOR FINES a 0051' N l6SCREEN ERNEST 8. WILSON INVENTOR.

BY Gaga-A. ("0. MAM Q Patented Feb. 2, 1943 UNET DRY SIZE AND W'EHOD OFMAKING Ernest S. Wilson, Holly Oak, Del, assignor to Hercules PowderCompany, Wilmington, De-L, a corporation of Delaware Application April.18, 1940, Serial No. 330,319

6 Claims. (Ci. roe-21s) This invention relates to improvements in drysizes, and more particularly to dry rosin size having a high apparentdensity and to a. method of making the size.

Dry size compositions, for example, dry rosin sizes used in the paper'making industry, have the advantage over paste sizes (containingusually about 30% moisture), in that they can be shipped at lowerfreight costs because of their lower moisture content. Also, dry sizescan be shipped in paper bags, weighing about 2 pounds for every 100pounds of size; while paste size must be shipped in drums, Weighingabout 28 pounds ior every 100 pounds of size. This saving in freight isvery desirable and is often a considerable item, particularly if thepaper mills and chemical plant, where the size is produced, are a longdistance apart.

Such dry sizes usually are prepared by mixing the ingredients in. liquidor paste form and then spraying the liquid or paste into a. current ofhot air or gas adapted to efiect flash evaporation and produce particlesof dry size. These particles are very porous or flufiy and only about 4to 12 pounds of size occupy a. cubic foot. This bulk maybe decreased toabout 15 pounds per cubic foot by forcing the size particles into bagsor containers by means of a plunger or ramrod which shatters theparticles into smaller ones that can then be packed closer together.

The foregoing method of packing dry size has several disadvantages. Thebulk is only decreased to about 15 pounds per cubic foot and this ratherlight material having a low apparent density requires bags ofconsiderable size, which increase the cost of packaging. In decreasingthe bulk by ramming the size into thebags, a' number of bags are broken,involving a direct money loss as well as a loss of time. The reductionin the size of the particles also causes a large amount of dust to bemade, and this dust. is disagreeable both at the chemical plant and thepaper mill.

An object of the present invention is to provide a dry size whichovercomes the foregoing difiiculties and disadvantages.

Another object is to provide a dry rosin size which has a high apparentdensity, is substantially free irom'dust. is free fiowingto facilitatepacking. andis readily dissolved.

A further object is to provide a simple inexpensive method of producingdry sizes having the foregoing advantageous characteristics.

Other and further objects will be obvious upon an understanding of theillustrative embodimerit about to be described, or will be indicated inthe appended claims, and various advantages not referred to herein willoccur to one skilled These objects, generally, may be accomplished byproducing dry size in a blow chamber in the customary manner, passingthe size particles through a roll crusher adapted to form flakes andthereby increase the apparent density of the size, and crushing andcompacting the flakes into smaller particles of still higher densityadapted to further reduce the bulk of the size.

Instead of forming flakes, briquettes, pellets, wa-

fers, or the like may be produced by suitable devices and these are thenground or crushed to form granular particles. The size particles arethen passed through a separator which removes dust and fines and returnsthem to the blow chamber or to the briquette forming devices. Theparticles are then screened to remove particles larger than apredetermined mesh and these are returned to the crushing device. Theresulting screened product is at least twice'as dense-as the blown size,is free from dust or fines, is granular and free flowing, and is readilydissolved. I

The productproduced by this process may be, for example, a granulateddry rosin size, although the process may be employed to increase theapparent density of any bulky dry size. By rosin size, as referred tohereinafter and in the claims, is meant the reaction product of gum orwood rosin or resin, or other materials having primarily an abietic,pimaric, sapinic, or other rosin acid content, and an alkali such ascaustic soda, soda ash, or any suitable alkali hydroxide. To thisreaction product may or may not be added additional materials such asinto a blow chamber H, in the customary man ner. The dry size produced,may contain between and 99% solids and the balance moisture, and usuallyhas a density of about 3 to 15 pounds per cubic foot.

This bulky size is then passed through suitable means l2 for compactingthe size particles by applying pressure thereon. If the size has asolids content of about 90 to 93%, this may be accomplished by passingthe particles through a number of pairs of rolls, for example, four, ina roll crusher. The rolls apply pressure to shape the size particlesinto flakes having a density of about at least 25 pounds per cubic foot.The

flaking operation serves to more than double the density of the drysize, whereby the bulk is greatly reduced. By compacting the size whilecontaining a small amount of moisture, for example, 7 to 10%, flakes arereadily formed without creating fines or dust which generally resultwhen size, practically free from moisture, is crushed. Size having sucha moisture content can be readily compacted without caking on oradhering to the rollers.

- If the size produced in the blow chamber has a solids content of about93 to 99% or higher, it

is desirable to slightly humidify the size to reduce the solids contentto 90 to 93% so that the sure exerted by the machine.

The briquettes or the like, or flakes, are then passed through a hammermill l4, preferably having its hammers set about of an inch from thebreaker plate and provided with a screen or cage having 3% of an inchperforations through which the material is forced. The hammer millserves to break the flakes or briquettes or the like into small granularparticles, and at the same time, when flakes are ground, serves tofurther compact the particles to increase the apparent density of thesize.

The size delivered by the hammer mill is then passed through a separator[5 which removes the dust and fines. The dust and fines may be mixedwith freshly blown size coming from the blow chamber or may be passedthrough the blow chamber and then passed through the system again. Theseparator preferably is of the roller mill aero-separator type, althoughany suitable separating device may be utilized. 4

The size particles from which dust and fines have been removed are thendelivered to a screening device I6. Preferably, this device is providedwith a screen designed to permit all particles of between about minustwenty mesh and about plus eighty (+80) mesh to pass therethrough andreject all particles of about plus twenty (+20) mesh. The largerparticles which are rejected are returned to the hammer mill I4, wherethey are reduced to finer particles, and are passed through theseparator again and then to the screen.

The particles which pass through the screen are collected as thefinished product. This product has an apparent density of about 35 to 45pounds per cubic foot, a solubility of about 90 to 120 seconds, and adry matter content of about 91 to 99%, but preferably 93 to 99%. Theproduct is granular, non-coalescing, and free flowing and can be readilypacked into containers by automatic machinery without bag breakage andat a small labor cost. Due to the increase in density or the reductionin bulk, smaller containers hold a given weight of size or containers ofa given volume will hold a greater weight of size. As a result, fewercontainers are required, thus decreasing the packaging costs. Thereduction in bulk also enables the size to be stored in a smallerstorage space. The size prepared in accordance with the invention isfree from dust and fines which is very beneficial, because the absenceof dust improves working conditions,

both at the'chemical plant and the paper mill. Also, the lack of dust inthe product minimizes the danger of spontaneous combustion. By firmlycompacting the blown size particles into granules, they lose theirflufi'y character and have a smaller exposed surface area, whereby theyare less susceptible to oxidation by air coming in contact therewith.

It will be understood that the details and examples hereinbefore setforth are illustrative only and that the invention as broadly describedand claimed is in no way limited thereby.

What I claim and desire to protect by Letters Patent is: 1

1. A method of making a high density dry size which comprises spraydrying liquid or paste size in a blow chamber to provide a size having amoisture content of between about 1 and 10%, compacting the sizeparticles to a density greater than about 20 pounds per cubic foot,reducing the size of the compacted particles, separating dust and finesfrom the reduced particles, returning dust and fines to the blowchamber, collecting particles of a size between about minus 20 and aboutplus mesh, and returning particles greater than said size for furtherreduction.

2. A method of making a high density dry size which comprisescompressing a dry saponified rosin size having an apparent densitybetween about 8 and about l5 pounds per cubic foot and a moisturecontent between about 1 and about 10 per cent to form compactedparticles having an apparent density greater than about 20 pounds percubic foot, and thereafter comminuting said particles to form granularparticles of predetermined size and having an apparent density of about35 pounds per cubic foot.

3. A dry size having an apparent density greater than about 20 poundsper cubic foot comprising essentially saponified rosin, said sizeconsisting essentially of particles of a size between about 20 and about+80 mesh and substantially free from dust.

4. A dry size having an apparent density between about 20 and about 45pounds per cubic foot comprising essentially, spray dried, compacted,and subsequently crushed, saponified rosin, said size consistingessentially of particles of a size between about -20 and about +80 meshand substantially free from dust.

5. A dry size having an apparent density of about 35 pounds per cubicfoot comprising essentially saponified rosin, said size consistingessentially of particles of a size between about --20 andtabout +80 meshand substantially free from dus 6. A dry size having an apparent densityof between about 30 and about 45 pounds per cubic foot comprisingessentially saponified rosin, said size consisting essentially ofparticles of a size between about 20 and about +80 mesh substantiallyfree from dust and having a moisture content between about 1% and about7%-and a solubility of about to seconds.

" ERNEST S. WILSON.

